Synergistic combination to improve grape color and to alter sensory characteristics of wine

ABSTRACT

This invention describes the use of S-abscisic acid (S-ABA) and ethylene producing-agents such as ethephon to synergistically improve red color in grapes and to alter the sensory characteristics of wine.

FIELD OF THE INVENTION

The present invention is directed to the use of a combination ofS-abscisic acid (S-ABA) or its salts with an ethylene producing chemicalsuch as ethephon, an ethylene biosynthesis precursor such as1-aminocyclopropane-1-carboxylic acid (ACC), an ethylene mimic such asacetylene, or ethylene to improve red color in grapes and to alter thesensory characteristics of wine.

BACKGROUND OF THE INVENTION

Fruit color is an important quality factor in red table and wine grapes.Commercial harvest requires sufficient levels of color in commerciallymature fruit and this can be a significant challenge for table grapegrowers. Fruit color development can be influenced by a number offactors including the grape cultivar, rootstock, plant vigor, climate,canopy management, light exposure, crop load, irrigation, fertilization,and plant growth regulators. Consequently, achieving optimal fruit colorrequires a programmatic approach rather than the use of a single tool orpractice.

The plant growth regulator ethephon, an ethylene-releasing chemical, isone tool that can be used to help improve color development (Jensen etal., 1975; Szyjewicz et al., 1984). However, ethephon has shortcomingsand risks. For example, in Crimson Seedless table grapes, ethephonefficacy is often inconsistent or poor. Multiple applications of highrates of ethephon may be required in order to achieve the desired levelof coloration, if it can even be achieved. In addition to beinginconsistent in its coloring effect, ethephon can cause berry softening,berry cracking or splitting and poor storage and shelf life (e.g. Jensenet al., 1975; Szyjewicz et al., 1984). Because of the importance offruit color development, there is a need for additional tools to helpimprove grape coloration.

S-Abscisic acid (S-ABA) is a naturally occurring plant hormone found inall higher plants (Cutler and Krochko, 1999. Finkelstein and Rock,2002). Levels of S-ABA in plants range from a few parts per billion insome aquatic plants to 10 parts per million in avocado fruit mesocarp(Milborrow, 1984). S-ABA is involved in many major processes duringplant growth and development including dormancy, germination, bud break,flowering, fruit set, general growth and development, stress tolerance,ripening, maturation, organ abscission, and senescence. S-ABA also playsan important role in plant tolerance to environmental stresses, such asdrought, cold, and excessive salinity.

One key role of S-ABA in regulating physiological responses of plants isto act as a signal of reduced water availability to reduce water loss,inhibit growth and induce adaptive responses. All these functions arerelated to stomatal closure of plant leaves (Raschke and Hedrich, 1985).When stomata close, plants conserve water to survive in environmentalstresses. However, stomatal closure also results in the reduction ofphotosynthesis, and thus growth. Stomatal closure is a rapid response ofplants to S-ABA. The mechanism of S-ABA that causes stomatal closure hasbeen studied, and the effect has been shown to be primarily due to theeffect of S-ABA on guard cell ion channels. Specifically, S-ABA blocksH⁺ efflux from and K⁺ influx into guard cells and promotes K⁺, Cl⁻, andmalate efflux and Ca²⁺ influx. The net effect of S-ABA is to reduce thetotal osmotica in the guard cells, which in turn decreases the watercontent in the cell. This causes the guard cells to lose their turgorand thus close the stomata (Assmann 2004). The closing of stomataresults in reduced transpiration of the plant leaf. In grapes,application of S-ABA has been reported to increase stomatal resistancein grapevines, thereby reducing the gas exchange and stomataltranspiration of the leaves (Düring and Broquedis, 1980).

The exogenous application of S-ABA to red grapes prior to harvest hasbeen shown to increase and accelerate the accumulation of anthocyaninsand increase the red color of the grape berry skins (e.g. Han et al.,1996; Lee et al., 1997; Kondo et al., 1998; Pepe et al., 2006). S-ABAhas been shown to be effective on red color varieties on which ethephonoften is not commercially effective (e.g. Crimson Seedless). At veryhigh rates, S-ABA may be associated with softened, split berries, orleaf yellowing.

The application of the plant growth hormones/plant growth regulatorsS-ABA and ethephon both stimulate development of red color by increasedaccumulation of anthocyanin pigment in the berries.

While both S-ABA and ethephon stimulate development of color, there arepotential shortcomings with each material. Ethephon performance can beinconsistent, dependent upon such factors as cultivar, vineyard, year,and environmental conditions. High levels of ethephon are known to causeproblems such as berry softening, berry splitting, and short shelf life(Jensen et al, 1975; Szyjewicz et al., 1984). S-ABA has not beenregistered and commercialized. Results from S-ABA field experiments showgood efficacy, but response can sometimes be variable.

SUMMARY OF THE INVENTION

The present invention is directed to the preharvest treatment of grapesafter fruit set with S-ABA or its salts and with an ethylene producingchemical such as ethephon, an ethylene biosynthesis precursor such asACC, an ethylene mimic such as acetylene, or ethylene. This combinationtreatment program accelerates and improves development of red color ingrape berries, resulting in a more rapid and consistent red color atlower rates compared to that which can be achieved with either compoundapplied alone at higher rates. Also, the use of the combination programat lower application rates lessens the risk of negative side effectsthat can occur with S-ABA or its salts and with ethylene-producingchemicals when these compounds are applied at higher rates. In addition,the combination program potentiates the positive effects of S-ABA onvarious sensory characteristics of wine quality.

DETAILED DESCRIPTION OF THE INVENTION

The present invention comprises the application of S-ABA or its saltsand ethylene producing-agents such as ethephon or ethylene to grapes orgrape vines to improve the development of red color and to alter varioussensory characteristics of wine quality. S-ABA or a salt of S-ABA isapplied to the grapevines by foliar spray including electrostatic sprayapplication to the grape berries and leaves, by application to the rootsof the grapevine through irrigation or fertigation methods, or byinjection into the grapevine. An ethylene producing-agent, ethylenebiosynthesis precursor, ethylene mimic, or ethylene is applied to thegrapevines by foliar spray application to the grape berries and leaves.

Experiments were conducted in which S-ABA and ethephon were applied tograpes alone or together, both as tank mix applications and sequentialapplications. Application of S-ABA and ethephon together at the sametime or separately in a sequential application program results in anovel, non-obvious effect in which more effective red coloration isachieved and lower rates of one or both compounds are used. Also, theapplication of ethephon with S-ABA on wine grapes potentiates thepositive effects of S-ABA on various sensory characteristics of winequality.

Combination treatments utilizing lower rates of either or both S-ABA andethephon result in better coloration than can be achieved with eithercompound alone at higher rates.

Combination treatments utilizing lower rates of either or both compoundsgive more effective, reliable, and more cost effective grape coloration.

Combination treatments utilizing lower rates of either or both compoundssafen grape coloration programs, minimizing potential negative effectsoften associated with ethephon and that are sometimes associated withhigh rates of S-ABA.

Although ethephon itself does not have a positive effect on sensorycharacteristics of wine quality, the combination of S-ABA and ethephongives higher quality wine than that achieved with S-ABA alone.

Abscisic acid (S-ABA; S-(+)-abscisic acid; +-ABA,(+)-(S)-cis,trans-abscisic acid, (+)-(S)-cis,trans-ABA; S-ABA;(S)-5-(1-hydroxy-2,6,6,-trimethyl-4-oxo-2-cyclohexen-1-yl)-3-methyl-(2Z,4E)-pentadienoicacid; CAS registry no. [21293-29-8]) is available from LomonBioTechnology Co., Ltd. (Shichuan, China).

Suitable salts of S-ABA include, but are not limited to sodium,potassium, calcium, ammonium, magnesium, and amine salts.

Ethephon is available from Bayer CropScience (GmbH, Frankfurt am Main,Germany).

S-ABA and ethephon are applied to the grapevines after berry set toachieve the desired effect on coloration of the grape berries and on thesensory characteristics of grape berries and wine. The presentlypreferred timing of the S-ABA application is during the period ofpre-veraison (approximately three weeks prior to veraison, whereveraison is defined as the beginning of berry softening) through thepost-veraison period until approximately one week prior to harvest.

Water is used as the carrier solvent for the applications. In thepresent invention, surfactants can be added to the chemical solution toimprove the performance of the S-ABA or its salts, particularly for thefoliar application. The water solution may contain between 0.01% to 0.5%v/v of a surfactant.

The presently preferred surfactant for S-ABA and S-ABA salt performanceis Brij 98 (polyoxyethylene (20) oleyl ether) available from Uniqema(Castle, Del.). Other surfactants are also useful in the presentinvention, including but not limited to, other surfactants in the Brijfamily (polyoxyethylene fatty alcohol ether) available from Uniqema(Castle, Del.), surfactants in the Tween family (Polyoxyethylenesorbitan ester) available from Uniqema (Castle, Del.), the Silwet family(Organosilicone) available from Momentive Performance Materials (Wilton,Conn.), the Triton family (Octylphenol ethoxylate) available from TheDow Chemical Company (Midland, Mich.), the Tomadol family (ethoxylatedlinear alcohol) available from Tomah3 Products, Inc. (Milton, Wis.), theMyrj family (Polyoxyethylene (POE) fatty acid ester) available fromUniqema (Castle, Del.), the Span family (Sorbitan ester) available fromUniqema (Castle, Del.), and the Trylox family (Ethoxylated Sorbitol andEthoxylated Sorbitol Ester) available from Cognis Corporation(Cincinnati, Ohio) as well as commercial surfactants such as LatronB-1956 (77.0% modified phthalic/glycerol alkyl resin and 23.0% Butylalcohol) available from Dow AgroSciences LLC (Indianapolis, 1N), Capsil(Blend of Polyether-polymethylsiloxane copolymer and nonionicsurfactant) available from Aquatrols (Paulsboro, N.J.), Agral 90 (Nonylphenol ethoxylate) available from Norac Concept. Inc. (Orleans, Ontario,Canada), Kinetic (99.00% proprietary blend of polyalkyleneoxide modifiedpolydimethylsiloxane and nonionic surfactants) available from SetreChemical Company (Memphis, Tenn.), and Regulaid (90.6% 2-butoxyethanol,poloxalene, monopropylene glycol) available from KALO, Inc. (OverlandPark, Kans.).

Other additives are also useful in the present invention including, butnot limited to, urea, nitrate salts such as ammonium nitrate, salts suchas calcium chloride, humectants such as poly(ethylene glycol), andvegetable oils such as soybean oil, corn oil, cotton oil, and palm oil.

The effective dose range of the active ingredient S-ABA varies dependingon the water volume applied as well as other factors such as the plantvariety, size, age, and application method. The S-ABA dose range is from1 to 800 mg/vine. The preferred S-ABA dose range for application is 20to 400 mg/vine. The preferred application volume for application is 5 to400 gallons/acre. Foliar spray applications are directed at the grapebunches to achieve complete coverage of the grape bunches and tomaximize the effect of the S-ABA application. Foliar spray applicationsinclude, but are not limited to airblast spray application orelectrostatic spray application. Soil applications are directed towardsthe rooting zone. Application methods include, but are not limited toapplication through irrigation/fertigation dripper line or applicationof S-ABA formulations or solutions to the soil at the base of the vine,followed by application of water to the soil to transport the S-ABA tothe roots of the vine. The preferred application timing for S-ABA isduring the period from veraison through 1 week before harvest.

The ethephon dose range is 1 to 800 mg/vine. The preferred ethephon doserange is 20 to 400 mg/vine. The preferred application volume is 5 to 400gallons/acre. Foliar applications are directed at the grape bunches. Thepreferred application timing for ethephon is the period from veraisonthrough 1 week before harvest.

The invention is demonstrated by following representative examples.

EXAMPLES Example 1

Plant material and application: A replicated field experiment wasconducted on the red table grape cultivar ‘Crimson Seedless’ in theCentral San Joaquin growing region of California, United States toevaluate the synergistic effect of S-ABA and ethephon on grapes. Thevineyard was 12 years old and on overhead trellis with a vine spacing of12 ft by 7 ft (518 vines/acre). Plot size was three vines/replicate,with six replicates/treatments. The area evaluated within each plot wasone center vine and two half vines on each side for a total of twovines. Applications were made seven days after veraison (beginning ofberry softening). On the day of application, red coloration wasdeveloping on about 10% of the berries. The nine treatments applied werecontrol, S-ABA alone (88, 292, or 877 mg/vine), ethephon alone (88, 292,or 877 mg/vine), and combinations of S-ABA and ethephon (88 mg/vineS-ABA and 88 mg/vine ethephon or 292 mg/vine S-ABA and 292 mg/vineethephon). All treatments were mixed with the adjuvant Latron B-1956(0.05% v/v; Dow AgroSciences LLC, Indianapolis, Ind.). Treatments wereapplied with a backpack mist blower at 200 gallons/acre (757 l/acre).

Evaluations: The total grape clusters were counted on the day ofapplication. After treatment, the plots were evaluated weekly for colordevelopment by counting the number of harvestable colored grape clustersin each plot. All harvestable colored clusters were removed 79 dayslater to eliminate over-mature clusters. The number of harvestablecolored grape clusters was expressed as cumulative harvestable clusters(number of harvestable clusters per two vines). Average berry firmness,weight and Brix (soluble solids) were evaluated 5 days later. Evaluationsamples consisted of 10 second shoulders (second lateral branch of themain rachis) from 10 different clusters selected randomly from eachplot. All berries in the evaluation samples were removed, counted, andweighed. A sub-sample of 20 to 30 berries was crushed for brix (solublesolids) analysis. Brix was measured with a handheld temperaturecompensating Leica Refractometer. An additional 10 berries were selectedrandomly for berry firmness. Berry firmness was determined by a handheld Wilson Penetrometer (0 to 1000 g) mounted on a stand with a 6 mmtip.

TABLE 1 Effect of S-ABA and ethephon alone and in combination on CrimsonSeedless grape number of cumulative harvestable clusters, firmness,Brix, and berry weight at harvest. Applications were made at veraisonplus seven days. Cumulative harvestable clusters Berry S-ABA Ethephon(no. per Firmness weight Brix (mg/vine) (mg/vine) two vines) (g) (g)(degrees) 0 0 7.3 850 4.9 19.0 88 0 11.8 766 5.0 20.0 292 0 38.0 759 5.419.5 877 0 43.8 663 6.1 19.1 0 88 9.2 765 5.2 20.6 0 292 15.7 766 5.820.3 0 877 40.2 709 5.4 20.1 88 88 24.7 781 5.5 19.9 292 292 50.2 7105.4 19.4

S-ABA alone and ethephon applied alone to Crimson Seedless grape bothincreased the cumulative harvestable cluster number in dose-dependentmanners for both compounds (Table 1). Thus, for S-ABA: Cumulativeharvestable clusters=12.5+(S-ABA (mg/vine)*0.056); r=0.75 and forethephon: Cumulative harvestable clusters=6.1+(ethephon(mg/vine)*0.040); r²=0.99. However, the combination treatment of 88mg/vine S-ABA and 88 mg/vine ethephon yielded a surprisingly high numberof cumulative harvestable clusters (24.7 harvestable clusters) comparedto either compound alone at 88 mg/vine (11.8 or 9.2 harvestable clustersfor S-ABA alone or ethephon alone, respectively).

Synergy was determined by an industrially accepted method (Kull et al.,1961, Applied Microbiology 9:538-541 and Robertson and Ramesh, 1998,U.S. Pat. No. 5,716,629). Synergy Index=Qa/QA+Qb/QB where:

Qa=dose of compound A in mg/vine, in the mixture, which produced an endpoint

QA=dose of compound A in mg/vine, acting alone, which produced an endpoint.

Qb=concentration of compound B in mg/vine, in the mixture, whichproduced an end point.

QB=dose of compound B in mg/vine, acting alone, which produced an endpoint.

Synergy, additivity, or antagonism are shown when the Synergy Index isless than one, equal to one, or greater than one, respectively. TheSynergy Index was calculated for the combination treatment of 88 mg/vineeach of S-ABA and ethephon with an end point of 24.7 cumulativeharvestable clusters. The calculated Synergy Index for this combinationtreated is 0.44 ( 88/337+ 88/484). Since the Synergy Index for thiscombination is less than one, the combination is synergistic.

The combination treatment of 292 mg/vine each of S-ABA and ethephonyielded the highest number of cumulative harvestable clusters (50.2) ofall treatments including S-ABA or ethephon at the highest rate of 877mg/vine (43.8 and 40.2, respectively).

Berry firmness for combination treatments of 88 or 292 mg/vine each ofS-ABA and ethephon (781 or 710 g, respectively) was greater than orequal to the firmness of the highest rates of S-ABA or ethephon (663 or709 g, respectively; Table 1). Thus, the combination treatments did notlead to excessive losses in berry firmness.

Berry weights and brix were greater for all S-ABA and ethephontreatments than the control (Table 1). Thus, the combination treatmentsdid not reduce berry size or brix compared to the control.

Example 2

A replicated field experiment was conducted on the red wine grapecultivar ‘Cabernet Sauvignon’ in the Riverland growing region of SouthAustralia. The vineyard was 19 years old with a vine spacing of 3 m by 3m. The plot size was nine vines/replicate with threereplicates/treatment. S-ABA (200 ppm) and ethephon (200 ppm) were foliarapplied to Cabernet Sauvignon grapes at 50-60% veraison using acommercial airblast sprayer. Treatments were mixed with the adjuvantAgral 600 (10 mL/100 L v/v; CropCare Australasia, Pty Ltd.).

Ethephon alone had little effect on sugar levels (Be), pH, titratableacidity, or anthocyanins of grapes measured at commercial harvest (Table2). Ethephon alone increased wine color density and phenolics. S-ABAalone had little effect on sugar levels (Be), pH, or titratable acidity.In this experiment, grape anthocyanins at harvest and wine color densitylevels in the S-ABA treatment were lower than in the untreated. S-ABAtreated wine received a higher wine assessment score by a trained winetasting panel. Although ethephon alone did not affect wine assessmentscores, the ethephon and S-ABA combination treatment increased winecolor density and phenolics more than S-ABA or ethephon alone and thewine received the most favorable wine assessment score by the trainedwine tasting panel. Thus, although ethephon had no effect on winequality by itself, ethephon surprisingly potentiated the positive effectof S-ABA on the sensory characteristics of wine.

TABLE 2 Effect of ethephon, S-ABA, and ethephon/S-ABA combination onCabernet Sauvignon grape and wine quality. Wine Grapes at harvest WineTitratable Anthocyanins color Wine Wine Be pH acidity (mg/g) densityphenolics assessment¹ Untreated 12.9 3.9 4.9 0.91 7.2 21.9 2.4 Ethephon(200 ppm) 13.1 3.9 4.9 0.91 8.0 27.1 2.3 at veraison ABA (200 ppm) 12.44.0 4.6 0.78 5.6 20.2 2.7 at veraison Ethephon + 12.9 4.0 4.7 0.94 8.729.4 3.1 ABA at veraison ¹Assessment made from 5 characteristics - Colorintensity, aroma intensity, body/fullness, flavor intensity, finish.Provisor Pty Ltd wine tasting panel scores.

The invention claimed is:
 1. A method of increasing cumulativeharvestable clusters in red grapes comprising applying a synergisticamount of S-abscisic acid or its salts and ethephon to red grapes afterveraison, wherein the amount of S-abscisic acid is from 88 to 292mg/vine, the amount of ethephon is from 88 to 292 mg/vine, and theapplication volume is 5 to 400 gallons/acre.
 2. The method of claim 1wherein the amount of S-abscisic acid or its salts is 88 mg/vine.
 3. Themethod of claim 1 wherein the amount of S-abscisic acid or its salts is292 mg/vine.
 4. The method of claim 1 wherein the amount of ethephon is88 mg/vine.
 5. The method of claim 1 wherein the amount of ethephon is292 mg/vine.
 6. The method of claim 1 wherein the S-abscisic acid saltis selected from the group consisting of sodium, potassium, calcium,ammonium, magnesium, and amine salts.
 7. The method of claim 1 whereinthe S-abscisic acid or its salts is applied by foliar spray, irrigation,or fertigation.
 8. The method of claim 7 wherein the S-abscisic acid orits salts is applied by foliar spray.
 9. The method of claim 7 whereinthe S-abscisic acid or its salts is applied by irrigation.
 10. Themethod of claim 7 wherein the S-abscisic acid or its salts is applied byfertigation.